WO1994000848A1 - Nuclear reactor fuel rod bundle with lockable head - Google Patents

Nuclear reactor fuel rod bundle with lockable head Download PDF

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Publication number
WO1994000848A1
WO1994000848A1 PCT/DE1993/000519 DE9300519W WO9400848A1 WO 1994000848 A1 WO1994000848 A1 WO 1994000848A1 DE 9300519 W DE9300519 W DE 9300519W WO 9400848 A1 WO9400848 A1 WO 9400848A1
Authority
WO
WIPO (PCT)
Prior art keywords
fuel
fuel assembly
fuel element
support plate
rod
Prior art date
Application number
PCT/DE1993/000519
Other languages
German (de)
French (fr)
Inventor
Peter Rau
Walter Sauermann
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to RU94046303/25A priority Critical patent/RU2111557C1/en
Priority to SK1574-94A priority patent/SK157494A3/en
Publication of WO1994000848A1 publication Critical patent/WO1994000848A1/en
Priority to BG99275A priority patent/BG61413B1/en
Priority to FI946132A priority patent/FI946132A/en

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Classifications

    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21CNUCLEAR REACTORS
    • G21C3/00Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/30Assemblies of a number of fuel elements in the form of a rigid unit
    • G21C3/32Bundles of parallel pin-, rod-, or tube-shaped fuel elements
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21CNUCLEAR REACTORS
    • G21C3/00Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/30Assemblies of a number of fuel elements in the form of a rigid unit
    • G21C3/32Bundles of parallel pin-, rod-, or tube-shaped fuel elements
    • G21C3/334Assembling, maintenance or repair of the bundles
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00Energy generation of nuclear origin
    • Y02E30/30Nuclear fission reactors

Definitions

  • the invention relates to a nuclear reactor fuel element
  • a lower fuel rod holding body which rests loosely within the elongated fuel element box on the fuel element end body, stands on the long fuel rods containing elongated fuel rods with one end and on which a rod projecting above the fuel rods in the fuel element box with its upper end is attached to its lower end,
  • a fuel assembly head which is inserted into the upper end of the fuel assembly box and which can be locked against rotation in the fuel assembly box by rotating about the longitudinal axis of the fuel assembly box.
  • the rod projecting over the fuel rods with its upper end is an elongated tube which is screwed onto the lower fuel rod holding body and which extends through the support plate at the upper end of the fuel assembly box.
  • Each fuel rod engages loosely in the support plate with its upper end, and a compression spring is arranged on each fuel rod at the upper end, which is supported at one end on the inside of the support plate and at the other end on a step on the outer surface of the fuel rod in question.
  • the the tube reaching through the support plate can be an instrumentation tube for receiving thermocouples and / or neutron flux measuring lances.
  • an elongated rod can also be guided through this tube and screwed to the lower fuel rod holder body by rotating it about its longitudinal axis.
  • This rod represents a lifting device with which the fuel rod holder body lying loosely on the end element of the fuel element, together with the tube, the fuel rods, lattice-shaped spacers through which the tube and fuel rods are guided, and the support plate can be pulled out of the fuel element box.
  • Such shifting to a sufficient extent may, however, be impossible or lead to damage to the fuel rods if the length of at least individual fuel rods has increased too much after a certain service life of the nuclear reactor fuel element in a nuclear reactor and therefore the coil springs on the rod ends during insertion of the support plate in the fuel assembly box before unlatching the tongues from the pockets on the fuel assembly head on block.
  • Such a blocking of individual coil springs can be avoided by sufficient clearance for these coil springs. This would mean, however, that for a given rod length of the fuel rods, the length of the nuclear reactor fuel must be correspondingly large.
  • the reactor pressure vessel with its internals in which the nuclear reactor fuel element is used must also be designed to be correspondingly high. This means relatively high costs.
  • the object of the invention is to further develop the proposed nuclear reactor fuel element and to avoid damaging the fuel rods when the fuel element head is rotated out of its latching position even if the length of the nuclear reactor fuel element is relatively short.
  • a nuclear reactor fuel element of the type mentioned at the outset is characterized in accordance with the invention in that the support plate rests on the upper end of the rod projecting above the fuel rods and in that a spring leg is arranged between the fuel element head and the support plate, which is located both on the fuel element head and on supports the support plate.
  • the support plate resting on the rod shields the fuel rods from their locked position when the fuel assembly head is turned. At the same time, however, the distance between the support plate and the fuel rods can only be chosen to be large enough to provide space for the extension of the fuel rods during the service life of the nuclear reactor fuel element in a nuclear reactor.
  • Figure 1 is divided into sections 1A and 1B and shows a nuclear reactor fuel element according to the invention, which is cut longitudinally.
  • FIG. 2 shows a cross section corresponding to the dash-dotted line II-II in FIG. 1.
  • FIG. 3 shows a partial longitudinal section along the dash-dotted line III-III in FIG. 2.
  • the nuclear reactor fuel element according to FIGS. 1 to 3 has a fuel element end body 2, which is a fuel element foot.
  • This fuel assembly end body 2 is a hollow body made of stainless steel, which has an outer contour in the form of a regular hexagon at its upper end.
  • the fuel assembly end body 2 engages in an elongated fuel assembly box 3, which consists of a zirconium alloy.
  • the inner cross section of the fuel assembly 3 has a contour which is also a regular hexagon, so that this fuel assembly 3 lies at its lower end with the inner surface snugly against the outer surface of the fuel assembly 2 at its upper end.
  • the fuel assembly box 3 is rigidly attached to this fuel assembly end body 2 with radially directed screws 4.
  • the lower fuel rod holder body 5 is composed of stainless steel sleeves arranged side by side in a net-like manner.
  • the longitudinal axes of these sleeves are parallel to the longitudinal axis 3a of the fuel assembly box 3. Furthermore, the outer sides of these sleeves are firmly connected to one another by webs made of stainless steel.
  • fuel rods 8 are arranged, each of which loosely stands on a web of the lower fuel rod holder body 5 with a lower rod end.
  • a sleeve 6 forms a hole in the lower fuel rod holder body 5 designed as a leadthrough It also has an internal thread.
  • An elongated tube 9 made of a zirconium alloy is screwed into each of seven such sleeves 6 and has an external thread corresponding to the internal thread of the relevant sleeve 6 at the screwed-in tube end. At this screwed-in tube end, the tube 9 in question closes off with a cap nut 10, which is screwed into the relevant sleeve 6 on the outside of the lower fuel rod holder body 5 facing the fuel assembly body 2.
  • Such a cap nut 10 engages in each case in the cavity of the Brennele ⁇ mentend stresses 2. It has a central passage 11 in the longitudinal direction of Brennel 'ementkastens 3 for a liquid Coolant in a nuclear reactor. It also has an internal thread. The other tube end of the tubes 9 of the same length is located above the inside of the lower fuel rod holder body 5.
  • Both the fuel rods 8 and the tubes 9 projecting beyond the fuel rods 8 are each guided through a mesh of grid-shaped spacers.
  • These grid-shaped spacers have an outer contour in the form of a regular hexagon and are the contour of the inner cross section of the
  • Adjusted fuel assembly 3 In the meshes of these spacers, which are arranged at right angles to the longitudinal axis 3a of the fuel assembly 3 at a distance from one another in the longitudinal direction of this fuel assembly 3, the fuel rods 8 are held in a force-fitting manner by means of contact springs and rigid contact knobs. At least one tube 9 is held in each spacer by torsion-proof bodies. Furthermore, the spacers themselves are fixed on the outside by means of molded bodies to at least one tube 9 in the longitudinal direction of the fuel assembly box 3. These spacers are not shown in Figure 1.
  • a support plate 13 made of stainless steel within this fuel assembly 3, the outer contour of which in the form of a regular hexagon is adapted to the contour of the inner cross section of the fuel assembly 3 and which rests loosely on the fuel assembly 2 lower fuel rod holder body 5 is composed of sleeves with an axis and webs parallel to the longitudinal direction of the fuel assembly box 3.
  • This support plate 13 is loosely guided in the fuel assembly 3 and is arranged at right angles to the longitudinal axis 3a of the fuel assembly 3. It lies loosely on the open pipe ends of the pipes 9, which are above the
  • the support plate 13 On its inside facing the inside of the lower fuel rod holder body 5, the support plate 13 has centering bodies 14, which are screwed into a sleeve of the support plate 13 and engage loosely but largely without play in the open upper end of one of the tubes 9.
  • the tubes 9 can also loosely engage in a centering recess (not shown) on the inside of the support plate 13.
  • a fuel element head 17 is inserted into the upper end of the fuel element box 3.
  • This fuel assembly head 17 is a hollow body which has six spring struts 20 on its side facing the support plate 13. As shown in FIG. 3 in particular, such a strut has a pin 21 which is parallel to the longitudinal axis 3a of the fuel assembly 3 and is arranged at a distance from this longitudinal axis 3a and which has an elongated hole 22 in the fuel assembly head 17 through which a transverse pin is held in the fuel assembly head 17 23 takes hold.
  • the pin 21 With its end located in the fuel assembly head 17, the pin 21 engages in a helical spring 24 which is mounted with a longitudinal axis parallel to the longitudinal axis of the pin within a bore which is located in the fuel assembly head 17 and is parallel to the longitudinal axis 3 a of the fuel assembly box 3.
  • This coil spring 24 is supported at one end on the bottom of this bore and at the other end on a shoulder on the outside of the pin 21.
  • the pin 21 of each of the spring struts 20 engages with its end located outside the fuel assembly head 17 into a latching recess 25 in the outside of the support plate 13 facing the fuel assembly head 17.
  • the pins 21 of the struts 20 are moved in the longitudinal direction of the fuel assembly box 3 with a tool guided through the cavity of the fuel assembly head 17, which engages behind a shoulder 21a in the lateral surface of the pins 21 of the struts 20 moved towards the fuel assembly head 17 into the fuel assembly head 17 until these pins 21 disengage from the latching recesses 25 in the support plate 13.
  • the fuel assembly head 17 can then be rotated from the locking position shown in FIGS. 1 and 2 about the longitudinal axis 3a of the fuel assembly box 3 into another end position in which the peripheral ribs 18 are unscrewed at the slots 19 and in which the fuel assembly head 17 is removed from the fuel assembly box 3 can be pulled out.
  • an elongated rod with an end having an external thread can be guided through a centrally arranged tube 9 to the union nut 10 and can be rotated about the longitudinal axis of the rod with the internal thread of the union nut 10 be screwed. Then, with the aid of the rod representing a hoist, the lower fuel rod holder body 5 loosely resting on the fuel element end body 2 together with all the tubes 9, the fuel rods 8, the grid-shaped spacers (not shown) and the support plate 13 can be pulled out of the fuel element box 3.

Abstract

One end of elongate fuel rods (8) stands inside an elongate fuel element chamber (3) on a lower fuel rod support (5), the lower end of which is also secured to a rod (9) projecting beyond the fuel rods (8). A supporting plate (13) freely guided in the fuel element chamber (3) lies on the upper end of the rod (9) to prevent damage to the fuel rods (8). A fuel element head (17) is inserted at the upper end of the fuel element chamber (3) and can be locked against torsion by turning about the longitudinal axis (3a) of said chamber (3). A spring arm (20) arranged between the fuel element head (17) and the supporting plate (13) bears on both the fuel element head (17) and the supporting plate (13). Consequently, dismantling does not necessitate a displacement of the supporting plate toward the lower fuel rod support, which could result in damage to the fuel rods below or would require that correspondingly greater distance be provided between them.

Description

KERNREAKTORBRENNSTABBUENDEL MIT VERRASTBAREM BRENNSTABBUENDELKOPFCORE REACTOR FUEL TUNE WITH LOCKING FUEL TUNE
Die Erfindung betrifft ein Kernreaktorbrennelement mitThe invention relates to a nuclear reactor fuel element
a) einem langgestreckten Brennelementkasten, an dessen Unterende ein Brennelementendkörper befestigt ist,a) an elongated fuel assembly box, at the lower end of which a fuel assembly end member is attached,
b) einem unteren Brennstabhaltekörper, der lose innerhalb des langgestreckten Brennelementkastens auf dem Brenn- elementendkörper aufliegt, auf dem Kernbrennstoff ent¬ haltende, langgestreckte Brennstäbe mit einem Ende auf¬ stehen und an dem ein die Brennstäbe im Brennelement- kasten mit seinem Oberende überragender Stab mit seinem Unterende befestigt ist,b) a lower fuel rod holding body, which rests loosely within the elongated fuel element box on the fuel element end body, stands on the long fuel rods containing elongated fuel rods with one end and on which a rod projecting above the fuel rods in the fuel element box with its upper end is attached to its lower end,
c) einer lose im Brennelementkasten an dessen Oberende ge¬ führten Stützplatte, sowiec) a support plate guided loosely in the fuel assembly box at its upper end, and
d) einem Brennelementkopf, der in das Oberende des Brenn- elementkastens eingesetzt und im Brennelementkasten durch Drehen um die Längsachse des Brennelementkastens verdrehungssicher verrastbar ist.d) a fuel assembly head which is inserted into the upper end of the fuel assembly box and which can be locked against rotation in the fuel assembly box by rotating about the longitudinal axis of the fuel assembly box.
Ein derartiges Kernreaktorbrennelement wurde bereits vor- geschlagen. Bei diesem vorgeschlagenen Kernreaktorbrenn- elemeπt ist der die Brennstäbe mit seinem Oberende überra¬ gende Stab ein langgestrecktes Rohr, das am unteren Brenn¬ stabhaltekörper festgeschraubt ist und das die Stützplatte am Oberende des Brennelementkastens durchgreift. Jeder Brennstab greift mit seinem Oberende lose in die Stützplat¬ te, und auf jedem Brennstab ist am Oberende eine Druckfeder angeordnet, die sich mit einem Ende an der Innenseite der Stützplatte und mit dem anderen Ende an einer Abstufung an der Außenfläche des betreffenden Brennstabs abstützt. Das die Stützplatte durchgreifende Rohr kann ein Instrumentie¬ rungsrohr zur Aufnahme von Thermoelementen und/oder Neu- tronenflußmeßlanzen sein. Durch dieses Rohr hindurch kann aber auch eine langgestreckte Stange geführt und durch Drehen um ihre Längsachse mit dem unteren Brennstabhalte¬ körper verschraubt werden. Diese Stange stellt ein Hebe¬ zeug dar, mit dem der auf dem Brenπelementendkörper lose aufliegende Brennstabhaltekörper samt dem Rohr, den Brenn¬ stäben, gitterförmigen Abstandhaltern, durch die Rohr und Brennstäbe geführt sind, und der Stützplatte aus dem Brenn¬ elementkasten herausgezogen werden kann.Such a nuclear reactor fuel element has already been proposed. In this proposed nuclear reactor fuel element, the rod projecting over the fuel rods with its upper end is an elongated tube which is screwed onto the lower fuel rod holding body and which extends through the support plate at the upper end of the fuel assembly box. Each fuel rod engages loosely in the support plate with its upper end, and a compression spring is arranged on each fuel rod at the upper end, which is supported at one end on the inside of the support plate and at the other end on a step on the outer surface of the fuel rod in question. The the tube reaching through the support plate can be an instrumentation tube for receiving thermocouples and / or neutron flux measuring lances. However, an elongated rod can also be guided through this tube and screwed to the lower fuel rod holder body by rotating it about its longitudinal axis. This rod represents a lifting device with which the fuel rod holder body lying loosely on the end element of the fuel element, together with the tube, the fuel rods, lattice-shaped spacers through which the tube and fuel rods are guided, and the support plate can be pulled out of the fuel element box.
Am Rand der Stützplatte befinden sich Zungen, die in Längs¬ richtung des Brennelementkastens die Außenseite dieser Stützplatte überragen und mit ihren Oberenden in Taschen des Brennelementkopfs greifen, wenn sich dieser im Brenn¬ elementkasten an dessen Oberende in Verrastposition befindet. Zum Lösen der Verrastung des Brennelementkopfs muß durch diesen Brennelementkopf ein Werkzeug geführt werden, mit dem die Stützplatte in Längsrichtung des Brenn¬ elementkastens in Richtung auf den unteren Brennstabhalte¬ körper verschoben und dadurch schließlich das Eingreifen der an der Stützplatte befindlichen Zungen in die Taschen am Brennelementkopf aufgehoben wird. Ein solches Verschie- ben in ausreichendem Maße kann jedoch unmöglich sein oder zu Beschädigungen an den Brennstäben führen, wenn die Länge zumindest einzelner Brennstäbe nach einer gewissen Stand¬ zeit des Kernreaktorbrennelements in einem Kernreaktor zu stark angewachsen ist und deswegen die Schraubenfedern auf den Stabenden beim Einschieben der Stützplatte in den Brenn¬ elementkasten vor dem Ausrasten der Zungen aus den Taschen am Brennelementkopf auf Block gehen. Ein solches auf Block-Gehen einzelner Schraubenfedern kann zwar durch ausreichend hohen Spielraum für diese Schrauben¬ federn vermieden werden. Dies würde aber bedeuten, daß bei vorgegebener Stablänge der Brennstäbe die Länge des Kern- reaktorbrennele ents entsprechend groß sein muß. Dement¬ sprechend hoch muß auch der Reaktordruckbeh lter mit seinen Einbauten ausgeführt sein, in dem das Kernreaktorbrennele¬ ment zum Einsatz kommt. Dies bedeutet relativ hohe Kosten.At the edge of the support plate there are tongues which project beyond the outside of this support plate in the longitudinal direction of the fuel assembly box and with their upper ends engage in pockets of the fuel assembly head when the fuel assembly head is in the locked position in the fuel assembly box at its upper end. In order to release the locking of the fuel assembly head, a tool must be passed through this fuel assembly head with which the support plate is displaced in the longitudinal direction of the fuel assembly box in the direction of the lower fuel rod holder and thereby ultimately the engagement of the tongues located on the support plate in the pockets on the fuel assembly head will be annulled. Such shifting to a sufficient extent may, however, be impossible or lead to damage to the fuel rods if the length of at least individual fuel rods has increased too much after a certain service life of the nuclear reactor fuel element in a nuclear reactor and therefore the coil springs on the rod ends during insertion of the support plate in the fuel assembly box before unlatching the tongues from the pockets on the fuel assembly head on block. Such a blocking of individual coil springs can be avoided by sufficient clearance for these coil springs. This would mean, however, that for a given rod length of the fuel rods, the length of the nuclear reactor fuel must be correspondingly large. The reactor pressure vessel with its internals in which the nuclear reactor fuel element is used must also be designed to be correspondingly high. This means relatively high costs.
Der Erfindung liegt die Aufgabe zugrunde, das vorgeschla¬ gene Kernreaktorbrennelement weiterzubilden und eine Be¬ schädigung der Brennstäbe beim Drehen des Brennelement¬ kopfs aus seiner Verrastposition auch dann zu vermeiden, wenn die Länge des Kernreaktorbrennelements verhältnis- mäßig gering ist.The object of the invention is to further develop the proposed nuclear reactor fuel element and to avoid damaging the fuel rods when the fuel element head is rotated out of its latching position even if the length of the nuclear reactor fuel element is relatively short.
Zur Lösung dieser Aufgabe ist ein Kernreaktorbrennelement der eingangs erwähnten Art erfindungsgemäß dadurch gekenn¬ zeichnet, daß die Stützplatte auf dem Oberende des die Brennstäbe überragenden Stabs aufliegt und daß zwischen Brennelementkopf und Stützplatte ein Feder¬ bein angeordnet ist, das sich sowohl am Brennelementkopf als auch an der Stützplatte abstützt.To achieve this object, a nuclear reactor fuel element of the type mentioned at the outset is characterized in accordance with the invention in that the support plate rests on the upper end of the rod projecting above the fuel rods and in that a spring leg is arranged between the fuel element head and the support plate, which is located both on the fuel element head and on supports the support plate.
Die auf dem Oberende des die Brennstäbe überragendenThe one on the top of the protruding from the fuel rods
Stabes aufliegende Stützplatte schirmt die Brennstäbe beim Drehen des Brennelementkopfs aus seiner Verrastposition ab. Zugleich kann aber auch der Abstand zwischen der Stütz¬ platte und den Brennstäben nur gerade so groß gewählt wer- den, daß er Raum für die Verlängerung der Brennstäbe wäh¬ rend der Standzeit des Kernreaktorbrennelements in einem Kernreaktor bietet. Die Erfindung und ihre Vorteile seien anhand der Zeichnung an einem Ausführungsbeispiel näher erläutert:The support plate resting on the rod shields the fuel rods from their locked position when the fuel assembly head is turned. At the same time, however, the distance between the support plate and the fuel rods can only be chosen to be large enough to provide space for the extension of the fuel rods during the service life of the nuclear reactor fuel element in a nuclear reactor. The invention and its advantages are explained in more detail with reference to the drawing using an exemplary embodiment:
Figur 1 ist in die Abschnitte 1A und 1B aufgeteilt und zeigt ein erfindungsgemäßes Kernreaktorbrennelement, das längsgeschnitten ist.Figure 1 is divided into sections 1A and 1B and shows a nuclear reactor fuel element according to the invention, which is cut longitudinally.
Figur 2 zeigt einen Querschnitt entsprechend der strich¬ punktierten Linie II-II in Figur 1.FIG. 2 shows a cross section corresponding to the dash-dotted line II-II in FIG. 1.
Figur 3 zeigt einen Teillängsschnitt entsprechend der strichpunktierten Linie III-III in Figur 2.FIG. 3 shows a partial longitudinal section along the dash-dotted line III-III in FIG. 2.
Das Kernreaktorbrennelement nach den Figuren 1 bis 3 hat einen Brennelementendkörper 2, der ein Brennelementfuß ist. Dieser Brennelementendkörper 2 ist ein Hohlkörper aus nicht rostendem Stahl, der an seinem Oberende einen Außen¬ umriß in Form eines regelmäßigen Sechsecks hat.The nuclear reactor fuel element according to FIGS. 1 to 3 has a fuel element end body 2, which is a fuel element foot. This fuel assembly end body 2 is a hollow body made of stainless steel, which has an outer contour in the form of a regular hexagon at its upper end.
Mit diesem Oberende greift der Brennelementendkörper 2 in einen langgestreckten Brennelementkasten 3, der aus einer Zirkoniumlegierung besteht. Der Innenquerschnitt des Brenn¬ elementkastens 3 hat eine Kontur, die ebenfalls ein regel¬ mäßiges Sechseck ist, so daß dieser Brennelementkasten 3 an seinem Unterende mit der Innenfläche satt an der Außen¬ fläche des Brennelementendkörpers 2 an dessen Oberende an¬ liegt. An diesem Brennelementendkörper 2 ist der Brenn¬ elementkasten 3 mit radial gerichteten Schrauben 4 starr befestigt.With this upper end, the fuel assembly end body 2 engages in an elongated fuel assembly box 3, which consists of a zirconium alloy. The inner cross section of the fuel assembly 3 has a contour which is also a regular hexagon, so that this fuel assembly 3 lies at its lower end with the inner surface snugly against the outer surface of the fuel assembly 2 at its upper end. The fuel assembly box 3 is rigidly attached to this fuel assembly end body 2 with radially directed screws 4.
Innerhalb des Brennelementkastens 3 befindet sich ein fla¬ cher , p lattenartiger unterer Brennstabhaltekörper 5 mit ei ner Außenkontur in Form eines regelmäßigen Sechsecks , die der Kontur des I nnenquerschnitts des Brennele entka- stens 3 angepaßt ist. Dieser untere Brennstabhaltekörper 5 ist rechtwinklig zur Längsachse 3a des Brennelementkastens 3 lose im Brennelementkasten 3 geführt und liegt lose auf dem Brennelementendkörper 2 auf.Inside the fuel assembly box 3 there is a flat, p-plate-like lower fuel rod holder body 5 with an outer contour in the form of a regular hexagon, which decouples the contour of the inner cross section of the fuel. least 3 is adjusted. This lower fuel rod holder body 5 is guided at right angles to the longitudinal axis 3a of the fuel assembly box 3 loosely in the fuel assembly box 3 and lies loosely on the fuel assembly end body 2.
Der untere Brennstabhaltekörper 5 ist aus nebeneinander angeordneten Hülsen aus rostfreiem Stahl netzartig zusam¬ mengesetzt. Die Längsachsen dieser Hülsen sind parallel zur Längsachse 3a des Brennelementkastens 3. Ferner sind die Außenseiten dieser Hülsen durch Stege aus rostfreiem Stahl miteinander fest verbunden.The lower fuel rod holder body 5 is composed of stainless steel sleeves arranged side by side in a net-like manner. The longitudinal axes of these sleeves are parallel to the longitudinal axis 3a of the fuel assembly box 3. Furthermore, the outer sides of these sleeves are firmly connected to one another by webs made of stainless steel.
Im Brennelementkasten 3 sind parallel zu dessen Längsachse 3a mit Kernbrennstoff gefüllte Brennstäbe 8 angeordnet, von denen jeder mit einem unteren Stabende auf einem Steg des unteren Brennstabhaltekörpers 5 lose aufsteht.In the fuel assembly 3 parallel to its longitudinal axis 3a fuel rods 8 are arranged, each of which loosely stands on a web of the lower fuel rod holder body 5 with a lower rod end.
Im unteren Brennstabhaltekörper 5 befinden sich Hülsen 6, von denen eine in Figur 1 erkennbar ist, mit größerem Innen- und Außendurchmesser als die anderen Hülsen dieses Brenn¬ stabhaltekörpers 5. Eine solche Hülse 6 bildet ein als Durchführung ausgebildetes Loch im unteren Brennstabhalte¬ körper 5. Ferner weist sie ein Innengewinde auf. In jeweils sieben solcher Hülsen 6 ist ein langgestrecktes Rohr 9 aus einer Zirkoniumlegierung eingeschraubt, das an dem einge¬ schraubten Rohrende ein dem Innengewinde der betreffenden Hülse 6 entsprechendes Außengewinde hat. An diesem einge¬ schraubten Rohrende schließt das betreffende Rohr 9 mit einer Hutmutter 10 ab, die auf der dem Brennelementkörper 2 zugewandten Außenseite des unteren Brennstabhaltekörpers 5 in die betreffende Hülse 6 eingeschraubt ist. Eine solche Hutmutter 10 greift jeweils in den Hohlraum des Brennele¬ mentendkörpers 2. Sie hat eine zentrale Durchführung 11 in Längsrichtung des Brennel'ementkastens 3 für ein flüssiges Kühlmittel in einem Kernreaktor. Ferner hat sie ein Innen¬ gewinde. Über der Innenseite des unteren Brennstabhalte¬ körpers 5 befindet sich das andere Rohrende der gleich langen Rohre 9.In the lower fuel rod holder body 5 there are sleeves 6, one of which can be seen in FIG. 1, with a larger inner and outer diameter than the other sleeves of this fuel rod holder body 5. Such a sleeve 6 forms a hole in the lower fuel rod holder body 5 designed as a leadthrough It also has an internal thread. An elongated tube 9 made of a zirconium alloy is screwed into each of seven such sleeves 6 and has an external thread corresponding to the internal thread of the relevant sleeve 6 at the screwed-in tube end. At this screwed-in tube end, the tube 9 in question closes off with a cap nut 10, which is screwed into the relevant sleeve 6 on the outside of the lower fuel rod holder body 5 facing the fuel assembly body 2. Such a cap nut 10 engages in each case in the cavity of the Brennele¬ mentendkörpers 2. It has a central passage 11 in the longitudinal direction of Brennel 'ementkastens 3 for a liquid Coolant in a nuclear reactor. It also has an internal thread. The other tube end of the tubes 9 of the same length is located above the inside of the lower fuel rod holder body 5.
Sowohl die Brennstäbe 8 als auch die die Brennstäbe 8 über¬ ragenden Rohre 9 sind jeweils durch eine Masche gitterför- miger Abstandhalter geführt. Diese gitterförmigen Abstand¬ halter haben eine Außenkontur in Form eines regelmäßigen Sechsecks und sind der Kontur des Innenquerschnitts desBoth the fuel rods 8 and the tubes 9 projecting beyond the fuel rods 8 are each guided through a mesh of grid-shaped spacers. These grid-shaped spacers have an outer contour in the form of a regular hexagon and are the contour of the inner cross section of the
Brennelementkastens 3 angepaßt. In den Maschen dieser Ab¬ standhalter, die rechtwinklig zur Längsachse 3a des Brenn¬ elementkastens 3 mit Abstand voneinander in Längsrichtung dieses Brennelementkastens 3 angeordnet sind, sind die Brennstäbe 8 mit Hilfe von Anlagefedern und starren Anlage¬ noppen kraftschlüssig gehalten. Mindestens ein Rohr 9 ist in jedem Abstandhalter durch Formkörper verdrehungssicher gehaltert. Ferner sind die Abstandhalter selbst durch Form¬ körper außen an mindestens einem Rohr 9 in Längsrichtung des Brennelementkastens 3 fixiert. Diese Abstandhalter sind in Figur 1 nicht dargestellt.Adjusted fuel assembly 3. In the meshes of these spacers, which are arranged at right angles to the longitudinal axis 3a of the fuel assembly 3 at a distance from one another in the longitudinal direction of this fuel assembly 3, the fuel rods 8 are held in a force-fitting manner by means of contact springs and rigid contact knobs. At least one tube 9 is held in each spacer by torsion-proof bodies. Furthermore, the spacers themselves are fixed on the outside by means of molded bodies to at least one tube 9 in the longitudinal direction of the fuel assembly box 3. These spacers are not shown in Figure 1.
Am Oberende des Brennelementkastens 3 befindet sich inner¬ halb dieses Brennelementkastens 3 eine Stützplatte 13 aus rostfreiem Stahl, deren Außenkontur in Form eines regel¬ mäßigen Sechsecks der Kontur des' Innenquerschnitts des Brennelementkastens 3 angepaßt ist und die ähnlich wie der lose auf dem Brennelementkörper 2 aufliegende untere Brenn¬ stabhaltekörper 5 aus Hülsen mit zur Längsrichtung des Brennelementkastens 3 paralleler Achse und Stegen zusammen¬ gesetzt ist. Diese Stützplatte 13 ist lose im Brennelement¬ kasten 3 geführt und rechtwinklig zur Längsachse 3a des Brennelementkastens 3 angeordnet. Sie liegt lose auf den offenen Rohrenden der Rohre 9 auf, die sich über derAt the upper end of the fuel assembly 3 there is a support plate 13 made of stainless steel within this fuel assembly 3, the outer contour of which in the form of a regular hexagon is adapted to the contour of the inner cross section of the fuel assembly 3 and which rests loosely on the fuel assembly 2 lower fuel rod holder body 5 is composed of sleeves with an axis and webs parallel to the longitudinal direction of the fuel assembly box 3. This support plate 13 is loosely guided in the fuel assembly 3 and is arranged at right angles to the longitudinal axis 3a of the fuel assembly 3. It lies loosely on the open pipe ends of the pipes 9, which are above the
Innenseite des unteren Brennstabhaltekörpers 5 befinden.Are located inside the lower fuel rod holder body 5.
Auf ihrer der Innenseite des unteren Brennstabhaltekörpers 5 zugewandten Innenseite weist die Stützplatte 13 Zentrier¬ körper 14 auf, die jeweils in eine Hülse der Stützplatte 13 eingeschraubt sind und lose, aber weitgehend spielfrei in das offene Oberende eines der Rohre 9 greifen. Die Rohre 9 können aber auch lose in eine nicht dargestellte Zentrier- ausnehmung auf der Innenseite der Stützplatte 13 greifen.On its inside facing the inside of the lower fuel rod holder body 5, the support plate 13 has centering bodies 14, which are screwed into a sleeve of the support plate 13 and engage loosely but largely without play in the open upper end of one of the tubes 9. The tubes 9 can also loosely engage in a centering recess (not shown) on the inside of the support plate 13.
In das Oberende des Brennelementkastens 3 ist ein Brenn¬ elementkopf 17 eingesetzt. Dieser Brennelementkopf 17 ist ein Hohlkörper, der auf seiner der Stützplatte 13 zuge- wandten Seite sechs Federbeine 20 aufweist. Wie insbeson¬ dere Figur 3 zeigt, weist ein solches Federbein einen zur Längsachse 3a des Brennelementkastens 3 parallelen, mit Abstand von dieser Längsachse 3a angeordneten Stift 21 auf, der im Brennelementkopf 17 ein Langloch 22 aufweist, durch das ein im Brennelementkopf 17 ortsfest gehalterter Querstift 23 greift. Mit seinem im Brennelementkopf 17 be¬ findlichen Ende greift der Stift 21 in eine Schraubenfeder 24, die mit zur Längsachse des Stifts paralleler Längs¬ achse innerhalb einer Bohrung gelagert ist, die sich im Brennelementkopf 17 befindet und parallel zur Längsachse 3a des Brennelementkastens 3 ist. Diese Schraubenfeder 24 stützt sich mit einem Ende am Boden dieser Bohrung und mit dem anderen Ende an einer Schulter außen am Stift 21 ab. Der Stift 21 jedes der Federbeine 20 greift mit seinem außerhalb des Brennelementkopfs 17 befindlichen Ende in eine Verrastausnehmung 25 in der dem Brennelementkopf 17 zugewandten Außenseite der Stützplatte 13. In der in Figur 1 dargestellten Verraststellung greift der Brennelementkopf 17 jeweils mit einer Umfangsrippe 18 auf seiner äußeren Mantelfläche in entsprechende Schlitze 19 innen am Brennelementkasten 3. Unter der Wirkung der auf Druck vorgespannten Schraubenfedern 24 der Federbeine 20 ist so der Brennelementkopf 17 in der in Figur 1 darge¬ stellten Verraststellung im Brennelementkasten 3 fixiert.A fuel element head 17 is inserted into the upper end of the fuel element box 3. This fuel assembly head 17 is a hollow body which has six spring struts 20 on its side facing the support plate 13. As shown in FIG. 3 in particular, such a strut has a pin 21 which is parallel to the longitudinal axis 3a of the fuel assembly 3 and is arranged at a distance from this longitudinal axis 3a and which has an elongated hole 22 in the fuel assembly head 17 through which a transverse pin is held in the fuel assembly head 17 23 takes hold. With its end located in the fuel assembly head 17, the pin 21 engages in a helical spring 24 which is mounted with a longitudinal axis parallel to the longitudinal axis of the pin within a bore which is located in the fuel assembly head 17 and is parallel to the longitudinal axis 3 a of the fuel assembly box 3. This coil spring 24 is supported at one end on the bottom of this bore and at the other end on a shoulder on the outside of the pin 21. The pin 21 of each of the spring struts 20 engages with its end located outside the fuel assembly head 17 into a latching recess 25 in the outside of the support plate 13 facing the fuel assembly head 17. In the locking position shown in Figure 1, the fuel assembly head 17 engages with a circumferential rib 18 on its outer circumferential surface in corresponding slots 19 on the inside of the fuel assembly box 3. Under the action of the compression springs 24 of the spring struts 20, the fuel assembly head 17 is shown in the figure 1 Darge¬ shown locking position in the fuel assembly 3 fixed.
Zum Entnehmen der Brennstäbe aus dem Brennelementkasten 3 werden die Stifte 21 der Federbeine 20 mit einem durch den Hohlraum des Brennelementkopfes 17 geführten Werkzeug, das eine Schulter 21a in der Mantelfläche der Stifte 21 der Federbeine 20 hintergreift, in Längsrichtung des Brenn¬ elementkastens 3 in Richtung auf den Brennelementkopf 17 zu in den Brennelementkopf 17 hinein verschoben, bis diese Stifte 21 aus den Verrastausnehmungen 25 in der Stützplat¬ te 13 ausrasten. Sodann kann der Brennelementkopf 17 aus der in Figuren 1 und 2 dargestellten Verraststellung um die Längsachse 3a des Brennelementkastens 3 in eine andere Endstellung gedreht werden, in der die Umfangsrippen 18 an den Schlitzen 19 herausgedreht sind und in der der Brenn¬ elementkopf 17 aus dem Brennelementkasten 3 herausgezogen werden kann. Nach dem Herausziehen des Brennelementkopfs 17 aus dem Brennelementkasten 3 kann eine langgestreckte Stange mit einem ein Außengewinde aufweisenden Ende durch ein zentral angeordnetes Rohr 9 hindurch bis zur Überwurf¬ mutter 10 geführt und durch Drehen um die Längsachse der Stange mit dem Innengewinde der Überwurfmutter 10 ver¬ schraubt werden. Hierauf kann mit Hilfe der ein Hebezeug darstellenden Stange der auf dem Brennelementendkörper 2 lose aufliegende untere Brennstabhaltekörpers 5 samt allen Rohren 9, den Brennstäben 8, den nicht dargestellten git- terförmigen Abstandhaltern und der Stützplatte 13 aus dem Brennelementkasten 3 herausgezogen werden. To remove the fuel rods from the fuel assembly 3, the pins 21 of the struts 20 are moved in the longitudinal direction of the fuel assembly box 3 with a tool guided through the cavity of the fuel assembly head 17, which engages behind a shoulder 21a in the lateral surface of the pins 21 of the struts 20 moved towards the fuel assembly head 17 into the fuel assembly head 17 until these pins 21 disengage from the latching recesses 25 in the support plate 13. The fuel assembly head 17 can then be rotated from the locking position shown in FIGS. 1 and 2 about the longitudinal axis 3a of the fuel assembly box 3 into another end position in which the peripheral ribs 18 are unscrewed at the slots 19 and in which the fuel assembly head 17 is removed from the fuel assembly box 3 can be pulled out. After the fuel assembly head 17 has been pulled out of the fuel assembly box 3, an elongated rod with an end having an external thread can be guided through a centrally arranged tube 9 to the union nut 10 and can be rotated about the longitudinal axis of the rod with the internal thread of the union nut 10 be screwed. Then, with the aid of the rod representing a hoist, the lower fuel rod holder body 5 loosely resting on the fuel element end body 2 together with all the tubes 9, the fuel rods 8, the grid-shaped spacers (not shown) and the support plate 13 can be pulled out of the fuel element box 3.

Claims

Patentansprüche Claims
1. Kernreaktorbrennelement mit1. Nuclear reactor fuel element with
a) einem langgestreckten Brennelementkasten, an dessen Unterende ein Brennelementendkörper befestigt ist,a) an elongated fuel assembly box, at the lower end of which a fuel assembly end member is attached,
b) einem unteren Brennstabhaltekörper, der lose innerhalb des langgestreckten Brennelementkastens auf dem Brenn- elementendkörper aufliegt, auf dem Kernbrennstoff ent¬ haltende, langgestreckte Brennstäbe mit einem Ende auf¬ stehen und an dem ein die Brennstäbe im Brennelement¬ kasten mit seinem Oberende überragender Stab mit seinem Unterende befestigt ist,b) a lower fuel rod holding body, which rests loosely within the elongated fuel element box on the fuel element end body, stands on the long fuel rods containing elongated fuel rods with one end and on which a rod projecting above the fuel rods in the fuel element box with its upper end also coexists is attached to its lower end,
c) einer lose im Brennelementkasten an dessen Oberende ge¬ führten Stützplatte, sowiec) a support plate guided loosely in the fuel assembly box at its upper end, and
d) einem Brennelementkopf, der in das Oberende des Brenn- ele entkastens eingesetzt und im Brennelementkasten durch Drehen um die Längsachse des Brennelementkastens verdrehungssicher verrastbar ist,d) a fuel assembly head which is inserted into the top end of the fuel assembly and which can be locked against rotation in the fuel assembly by rotating about the longitudinal axis of the fuel assembly,
d a d u r c h g e k e n n z e i c h n e t , daß die Stützplatte (13) auf dem Oberende des die Brennstäbe (8) überragenden Stabs (9) aufliegt und daß zwischen Brennelementkopf (17) und Stützplatte (13) ein Federbein (20) angeordnet ist, das sich sowohl am Brennelementkopf (17) als auch an der Stützplatte (13) abstützt.characterized in that the support plate (13) rests on the upper end of the rod (9) projecting above the fuel rods (8) and in that a spring strut (20) is arranged between the fuel element head (17) and the support plate (13), which is located on both the fuel element head (17 ) and on the support plate (13).
2. Kernreaktorbrennelement nach Patentanspruch 1, d a d u r c h g e k e n n z e i c h n e t , daß das Federbein (20) mit einem Ende am Brennelementkopf (17) befestigt ist und mit dem anderen Ende lose in eine2. Nuclear reactor fuel element according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the strut (20) is attached at one end to the fuel assembly head (17) and with the other end loosely in one
Verrastausneh ung (25) in der Stützplatte (13) greift. Verrastausneh ung (25) in the support plate (13) engages.
3. Kernreaktorbrennelement nach Anspruch 2, d a d u r c h g e k e n n z e i c h n e t , daß das Federbein (20) mit Abstand parallel zur Längsachse (3a) des Brennelementkastens (3) angeordnet ist.3. Nuclear reactor fuel element according to claim 2, that the spring strut (20) is arranged at a distance parallel to the longitudinal axis (3a) of the fuel element box (3).
4. Kernreaktorbrennelement nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t , daß die Stützplatte (13) mit einem Zentrierkörper (14) lose in das Oberende des Stabes (9) greift.4. Nuclear reactor fuel element according to claim 1, that the supporting plate (13) with a centering body (14) loosely engages in the upper end of the rod (9).
5. Kernreaktorbrennelement nach Patentanspruch 1, d a d u r c h g e k e n n z e i c h n e t , daß der Stab (9) lose in eine Zentrierausnehmung in der Stütz¬ platte (13) greift. 5. Nuclear reactor fuel element according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the rod (9) loosely engages in a centering recess in the support plate (13).
PCT/DE1993/000519 1992-06-29 1993-06-16 Nuclear reactor fuel rod bundle with lockable head WO1994000848A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
RU94046303/25A RU2111557C1 (en) 1992-06-29 1993-06-16 Nuclear reactor fuel element
SK1574-94A SK157494A3 (en) 1992-06-29 1993-06-16 Nuclear reactor fuel element
BG99275A BG61413B1 (en) 1992-06-29 1994-12-19 Fuel element of a nuclear reactor
FI946132A FI946132A (en) 1992-06-29 1994-12-28 Nuclear reactor fuel element

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4221301.0 1992-06-29
DE4221301A DE4221301A1 (en) 1992-06-29 1992-06-29 Nuclear reactor fuel element

Publications (1)

Publication Number Publication Date
WO1994000848A1 true WO1994000848A1 (en) 1994-01-06

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BG (1) BG61413B1 (en)
CZ (1) CZ281841B6 (en)
DE (1) DE4221301A1 (en)
FI (1) FI946132A (en)
HU (1) HU214072B (en)
RU (1) RU2111557C1 (en)
SK (1) SK157494A3 (en)
WO (1) WO1994000848A1 (en)

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Publication number Priority date Publication date Assignee Title
WO1996003752A1 (en) * 1994-07-22 1996-02-08 Siemens Aktiengesellschaft Fuel rod assembly put together by means of pegs

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SU708830A1 (en) * 1978-06-15 1983-04-07 Предприятие П/Я Г-4285 Fuel assembly of nuclear reactor
SU784570A1 (en) * 1979-03-28 1983-04-07 Предприятие П/Я Г-4285 Top end part of fuel assembly
SU665556A1 (en) * 1977-12-19 1985-05-15 Предприятие П/Я М-5881 Heat-evolving assembly
JPH02195295A (en) * 1989-01-25 1990-08-01 Nuclear Fuel Ind Ltd Atomic fuel assembly
DE4041349A1 (en) * 1990-12-21 1992-06-25 Siemens Ag Nuclear fuel element - with liftable holder from casing, allowing fuel rod inspection or exchange
WO1992010839A1 (en) * 1990-12-05 1992-06-25 Siemens Aktiengesellschaft Fuel or control element with a releasable lock between casing and top or bottom of the element

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SU665556A1 (en) * 1977-12-19 1985-05-15 Предприятие П/Я М-5881 Heat-evolving assembly
SU708830A1 (en) * 1978-06-15 1983-04-07 Предприятие П/Я Г-4285 Fuel assembly of nuclear reactor
SU784570A1 (en) * 1979-03-28 1983-04-07 Предприятие П/Я Г-4285 Top end part of fuel assembly
JPH02195295A (en) * 1989-01-25 1990-08-01 Nuclear Fuel Ind Ltd Atomic fuel assembly
WO1992010839A1 (en) * 1990-12-05 1992-06-25 Siemens Aktiengesellschaft Fuel or control element with a releasable lock between casing and top or bottom of the element
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996003752A1 (en) * 1994-07-22 1996-02-08 Siemens Aktiengesellschaft Fuel rod assembly put together by means of pegs
US5787143A (en) * 1994-07-22 1998-07-28 Siemens Aktiengesellchaft Nuclear reactor fuel assembly

Also Published As

Publication number Publication date
CZ281841B6 (en) 1997-02-12
SK157494A3 (en) 1995-06-07
RU94046303A (en) 1996-10-20
BG99275A (en) 1995-11-30
HU214072B (en) 1997-12-29
BG61413B1 (en) 1997-07-31
FI946132A0 (en) 1994-12-28
FI946132A (en) 1994-12-28
DE4221301A1 (en) 1994-01-05
HUT69811A (en) 1995-09-28
RU2111557C1 (en) 1998-05-20
CZ316094A3 (en) 1995-04-12

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